A stereoscopic display device produces a three-dimensional image, similar to an actual object, as seen by a human being, by providing different images to the left and right eyes. In general, a human being perceives three-dimensional objects because the left and right eyes asynchronously recognize objects. That is, because the eyes of human beings are spaced apart by about 65 mm, an object is viewed on different angles by respective eyes, causing binocular parallax. Due to the phenomenon of binocular parallax, objects are perceived three-dimensionally. Therefore, by providing the eyes of an observer with images apparently seen on different angles, three-dimensional images may be realized.
A typical stereoscopic display device may be classified into a glasses type stereoscopic display device and a glasses-free type stereoscopic display device. According to the glasses type stereoscopic display device, a left-view image and a right-view image having different polarization characteristics are outputted from a display device, the left-view image and the right-view image being projected to respective left-eye and right-eye lenses of glasses to which polarizing plates having different transmission axes are attached, to thereby allow a user to perceive objects three-dimensionally. Although the inconvenience of wearing glasses exists with regard to the glasses type stereoscopic display device, limitations on viewing angles are relatively small, and fabrication is relatively easy.
In general, the glasses type stereoscopic display device includes a display panel for generating a left-view image and a right-view image, and a polarization separating unit attached to the display panel for imparting different polarization states to the left-view and right-view images.
The polarization separating unit is manufactured by directly patterning a polarizing plate itself, or by attaching a retardation plate (optical filter), patterned to correspond to left-view and right-view images, to the polarizing plate.
According to the method of patterning the polarizing plate itself, because a chemical etching process should be performed, a manufacturing process may be complicated and a production costs are high. Therefore, recently, the method of attaching a patterned retardation plate (optical filter) to the polarizing plate has been widely used. For patterning the retardation plate, a method of partially eliminating a retardation layer using laser etching after forming the retardation layer on a substrate, or a method of selectively printing an alignment layer and a liquid crystal layer on a substrate using a roll printing technique is used. However, according to the laser etching technique, the retardation layer may be easily damaged or deformed due to heat, thereby increasing a defect ratio. According to the roll printing technique, an optical filter may be formed in a relatively simple process. However, since the roll printing technique is a type of contact printing technique, a printing plate surface may be easily contaminated during printing, and a new printing plate should be used for adjusting a line width. Therefore, the roll printing technique is not suitable for small quantity batch production.
Further, for clear stereoscopic images, an optical filter pattern should have the same line width as a pixel of the display device. However, according to an optical filter manufactured by using a typical method, it is difficult to correctly match the pixels of the display device and the optical filter pattern. Further, as illustrated in FIG. 1, a liquid crystal layer disposed on an alignment layer flows down along a side of the alignment layer, and thus, the liquid crystal layer becomes thinner and is mixed with an adjacent liquid crystal layer. Therefore, the liquid crystal layer cannot contact the alignment layer, thereby generating a non-aligned portion and limiting the realization of high-quality stereoscopic images.